US Patent Application Publication No. 2013/0164175 discloses a measurement apparatus configured to measure a specimen such as blood by using a disk-shaped cartridge 610, as shown in FIG. 36. In this measurement apparatus, the cartridge 610, in which a chamber 620 for storing a measurement sample therein is formed, is used. In addition, the measurement apparatus is provided with: a rotator 630 that supports and rotates the cartridge 610; a light emitter 640 that applies light to the measurement sample in the chamber 620; and a photodetector 650 that detects light having passed through the measurement sample. In this measurement apparatus, a camera is used as the photodetector 650. An image of the light having passed through the measurement sample in the chamber 620 is taken by the camera, and the measurement sample is analyzed on the basis of change and/or density of the color of the taken image.
In a measurement apparatus as described above, when a plurality of chambers are provided in a cartridge and a reaction between a specimen and a reagent is promoted while transferring a measurement sample between the chambers, the position of the measurement sample transferred to each chamber is not always the same. In this case, for example, the measurement sample may be positioned at the center of the chamber or may be positioned at the edge of the chamber. Such a displacement of the measurement sample in the chamber may cause variation in the position of the measurement sample with respect to the photodetector.